The Buddhist Karla Caves lie in the western ghats, about 114 kms. away from Mumbai. They are carved out almost 2,000 years ago - and have large collection of Chaityas (halls).The magnificent hall that adorns the main cave reflects the high degree of architectural skills of the artisans who carved and embellished the caves on such a difficult terrain. Although asexquisite as the more famous Ajanta and Ellora caves, these caves are less crowded and make for an extremely pleasant outing. While at Karla, the Bhaja and Bedsa caves are worth a detour. The beautifully carved Chaityas and Viharas (monasteries) take you on a
journey back in time, narrating stories of the past.
The rock-cut caves are the most interesting part of Buddhist style of architecture. Cool in summer, cozy in winter, these rock-cut caves are particularly well adapted to Indian conditions, both material and spiritual. Apart from the climatic suitability, the concept of the cave strikes one of the fundamental chords of Indian spirituality-of being one with nature. 
. At the same time, it must not be forgotten that for every rock-cut monastery there must have been scores of structural buildings of which no trace has survived. So, the Buddhist monks built not just shelters but everlasting tributes to their beliefs. The Buddhist monks diligently carved out replicas of stupas, chaitya halls, images and shrines out of rocky hillsides. The Karla Caves in Maharasthra are one of the finest examples of this architectural style.
The Buddhist monks generally chose isolated rocky outcrops and hillsides to make rock-cut caves, which housed prayer halls or chaityas within them. From the late 2nd century BC until the mid 2nd century AD, thousands of caves like Karla were excavated in the Sahyadri Hills. They were apparently meant for all Buddhist communities.
. These cave sites were not randomly chosen. They were selected in accordance with the Buddhist prescription that the holy men should live neither too near nor too far from the cities-not too near to be distracted by material life, nor too far to make begging rounds impractical or to put the monks out of reach of people. Naturally, the existence of a natural cave was another determining factor. From this point of view, Karla was excellently situated. It was a natural cave and also used to be along one of the major caravan trading routes.
The Karla caves are centuries old and probably have the largest collection of Chaityas. The caves with Viharas were excavated for the Buddhist monks, who used to gather here during the monsoons. Built in the time of the Hinayana sect, during the Satavahanas rule, these caves do not actually show the Buddha.
A steep 350-step climb leads to the caves. At the entrance is a recently built temple; accompanied by a pillar from the Buddhist period. The facade of the caves is formed by carved temple screens, sculpted with railing ornaments and human couples. Outer and inner screens form an antechamber to the main cave. 
.The panels of the wooden doors and windows are finely decorated with intricate sculptures of couples embracing. You will also come across a 45-meter (148 foot) long Chaitya, possibly the finest of its kind in the country.
By the seventh century AD, the Mahayana sect took over and representations of Buddha became more common. By the central doorway, you'll find sculptures of the Buddha preaching while seated on a lion-supported throne, along with magnificent carvings of three elephants, On each side, fifteen pillars separate the narrow aisles from the central arch. The pillars are adorned with motfs of elephants, men and women riding, etc. The large number of cave shrines abandoned at various stages of construction gives us a broad outline of the manner in which they were dug out. Work proceeded from the top downwards, eliminating the need for scaffolding. Caves were created in groups to provide accommodation for outside workers, since such undertakings were beyond the resources of a very small religious community. They consist of two types: chaitya halls and viharas. Chaitya halls were for congregational worship (an activity that fundamentally distinguishes Buddhism from Hinduism). 
.The viharas were the dwelling place of the monks and usually consisted of cells cut into the walls around three sides of a hall-all very austere and demanding great hardships from the body. One enduring features of these caves is the
arched entrances and vaulted interiors.
The actual process of construction is fascinating. The chosen hillside was cleared of shrubs and other growth. The parallel tunnels were then run to the desired depth and timber wedges driven vertically into the exposed rock at convenient centers. When moistened, these wedges expanded and dislodged large chunks of stone that were removed through the mouth of the cave. Thus the rock was exposed. At this point all the exposed rock would be chiseled and polished and only then would the workmen continue the excavation. Gradually, with mere one-fourth-inch chisels and hammers as the tools, the excavation was carried on from the ceiling downward-a tedious process but one that has survived, as Karla testifies. Once excavated, timber trelliswork and balconies were added as trimmings.